Storage utilities for Android

Storage.kt

package com.yrezgui.videoplayer

import android.annotation.SuppressLint
import android.content.Context
import android.os.Build.VERSION
import android.os.Build.VERSION_CODES
import android.os.Environment
import android.os.storage.StorageManager
import android.os.storage.StorageVolume
import androidx.annotation.RequiresApi
import java.io.File

enum class VolumeType {
    EMULATED, REMOVABLE, MIXED
}

data class VolumeResource(
    val type: VolumeType,
    val path: String
)

@RequiresApi(api = VERSION_CODES.KITKAT)
private fun getVolumesApi19(): List<VolumeResource> {

    val path = Environment.getExternalStorageDirectory()
    val isRemovable = Environment.isExternalStorageRemovable()
    val isEmulated = Environment.isExternalStorageEmulated()

    val volumeType = when {
        isEmulated && isRemovable -> VolumeType.MIXED
        isEmulated && !isRemovable -> VolumeType.EMULATED
        else -> VolumeType.REMOVABLE
    }

    return listOf(VolumeResource(type = volumeType, path = path.toString()))
}

@RequiresApi(api = VERSION_CODES.LOLLIPOP)
fun getVolumesApi21(context: Context): List<VolumeResource> {

    // e.g. /storage/emulated/0/Android/media/com.yrezgui.videoplayer
    // e.g. /storage/sdcard/Android/media/com.yrezgui.videoplayer
    val volumeRootFolders = context.externalMediaDirs.map {
        it.parentFile?.parentFile?.parentFile
    }

    return volumeRootFolders.filterNotNull().map { folder ->
        val folderState = Environment.getStorageState(folder)
        val isEmulated = Environment.isExternalStorageEmulated(folder)
        val isRemovable = Environment.isExternalStorageRemovable(folder)

        val volumeType = when {
            isEmulated && isRemovable -> VolumeType.MIXED
            isEmulated && !isRemovable -> VolumeType.EMULATED
            else -> VolumeType.REMOVABLE
        }

        VolumeResource(type = volumeType, path = folder.toString())
    }
}

@RequiresApi(api = VERSION_CODES.R)
private fun getVolumesApi30(context: Context): List<VolumeResource> {
    val storageManager = context.getSystemService(Context.STORAGE_SERVICE) as StorageManager

    return storageManager.storageVolumes.map {
        val volumeType = when {
            it.isEmulated && it.isRemovable -> VolumeType.MIXED
            it.isEmulated && !it.isRemovable -> VolumeType.EMULATED
            else -> VolumeType.REMOVABLE
        }

        VolumeResource(type = volumeType, path = it.directory!!.toString())
    }
}

fun getVolumes(context: Context): List<VolumeResource> {
    return when {
        VERSION.SDK_INT >= VERSION_CODES.R -> getVolumesApi30(context)
        VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP -> getVolumesApi21(context)
        else -> getVolumesApi19()
    }
}

fun getFiles(folder: File): List<File> {
    val files = folder.listFiles()?.asSequence() ?: emptySequence<File>()

    return files
        .filter(::removeHiddenFiles)
        .filter(::removeNonVideoFiles)
        .sortedByDescending { it.isDirectory }
        .toList()
}

private fun removeHiddenFiles(file: File): Boolean {
    return !file.isHidden || file.name.first() != '.'
}

val VIDEO_EXTENSIONS = arrayOf("mpg", "mpeg", "mp4", "asf", "wma", "wmv", "avi", "3gpp", "3gpp2")
private fun removeNonVideoFiles(file: File): Boolean {
    return file.isDirectory || (file.isFile && VIDEO_EXTENSIONS.contains(file.extension))
}